Biological action of estrogen on the epididymis of prepubertal rhesus monkey.

An estrogen binding protein has been demonstrated in the cytosol of the epididymis and caudal lobe of prostate of immature rhesus monkey. Scatchard plot analyses were linear, suggesting a single class of high affinity binding sites for the synthetic estrogen, R-2858 (Moxestrol) with a Kd of 5.88 X 10(-10) mol/l and a concentration of binding sites of 17.0 +/- 4.4 fmol/mg cytosol protein in the epididymis. In the prostate, the concentration of binding sites was 19.7 +/- 3.6 fmol/mg cytosol protein with a Kd of 5.42 X 10(-10) mol/l. In immature castrated monkeys, administration of estradiol dipropionate caused a significant increase in the weight, total protein and sialic acid content of the epididymis. This biological action of estrogen on the epididymis is presumably mediated via estrogen receptor.